JPS6071502A - Purifying apparatus of gaseous hydrogen - Google Patents

Abstract

PURPOSE:To prevent the deterioration of a metallic hydride and to obtain purified gas stably for a long period by refining crude gaseous hydrogen into purified gaseous hydrogen with passing the crude gaseous hydrogen through a catalyst reactor and an adsorbent vessel, thereafter through a metallic hydride vessel. CONSTITUTION:The crude gaseous hydrogen from a storage vessel 1 for hydrogen is adjusted to suitable pressure by a valve 2, and introduced via a pipe 3 to a catalyst reactor 4 in which oxygen contained in said crude hydrogen is changed into water catalytically. The treated gaseous hydrogen is introduced to an adsorbent vessel 7 via a pipe 6 provided with a valve 5, and the water contained in the gaseous hydrogen produced at the reactor 4 is adsorbed and removed by an adsorbent. The gaseous hydrogen treated in the adsorbent vessel is packed into a metallic hydride vessel 10 under pressure via a pipe 9. Thereafter, when a part of the gas packe in the vessel is purged by closing a valve 8 and a valve 12 provided to a supplying pipe 11 of the purified gaseous hydrogen and by opening a purging valve 14 of purging pipe 13, the impure gas is removed from the vessel.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a hydrogen gas purification apparatus, and more particularly to a hydrogen gas purification apparatus using metal hydrides.

Hydrogen gas is generally produced industrially by decomposition of hydrocarbons and ammonia, or water electrolysis, but such hydrogen gas contains impurity gases such as inert gases such as helium and argon, as well as oxygen, water, and nitrogen. , - Since it contains carbon oxide, carbon dioxide, sulfur dioxide, nitrogen oxide, methane, etc., for example, in the semiconductor industry, metal processing industry, or instrumental analysis, after the crude hydrogen gas is purified, I am using it.

Various methods for purifying hydrogen gas have been known in the past, but in recent years certain metals or alloys have selectively absorbed hydrogen gas to form metal hydrides. Hydrogen gas purification using the property of reversibly releasing hydrogen has been proposed. This method involves filling a container filled with metal hydride with crude hydrogen gas under a predetermined pressure, allowing hydrogen gas to be selectively occluded by the metal hydride, and then making sure that hydrogen gas is not occluded by the metal hydride in the container. Remaining impurity gas is removed by purging the container, and then hydrogen is released at the hydrogen equilibrium decomposition pressure of the metal hydride to obtain purified hydrogen gas.

However, generally commercially available crude hydrogen gas contains various impurity gases as described above, and among these, water and oxygen are particularly susceptible to metal hydrides such as rare earth element alloys, magnesium alloys, iron alloys, etc. When these are used, they are deteriorated by oxidation and their hydrogen storage capacity is reduced over time, so that the Ti production degree of the obtained hydrogen gas is also reduced.

In addition to oxygen and water, impurity oxide gases such as carbon dioxide, carbon dioxide, sulfur dioxide, and nitrogen oxides are also strongly chemically adsorbed onto the surface of metal hydrides, inhibiting the hydrogen absorption and release reactions of metal hydrides. In addition to having an inhibiting poisoning effect, due to its strong adsorption properties, it cannot be removed by a purge operation after filling the container with hydrogen gas.
If the amount of these adsorbed on the surface of the metal hydride increases, these impurity gases will be desorbed from the metal hydride when hydrogen is released from the metal hydride, contaminating the purified hydrogen gas obtained. The purity of the gas will pulsate.

The present invention was made to solve the above-mentioned problems in hydrogen gas purification using metal hydrides, and it is possible to stably obtain purified hydrogen gas over a long period of time without deterioration of metal hydrides. The purpose is to provide hydrogen gas purification equipment.

The hydrogen gas purification apparatus according to the present invention includes a catalytic reactor for catalytically converting oxygen in crude hydrogen gas into water, an adsorbent container for adsorbing and removing water in the hydrogen from this reactor, and this adsorbent container. The present invention is characterized in that it comprises a metal hydride container filled with a metal hydride capable of absorbing and releasing hydrogen gas from the metal hydride container, and purified hydrogen gas is obtained from the metal hydride container.

The present invention will be explained below based on FIG. 1 showing an embodiment.

In the apparatus of the present invention, the crude hydrogen gas from 1 to a hydrogen storage container, for example, is adjusted to an appropriate pressure by a valve 2, and then passes through a pipe 3 to catalytically remove oxygen from the crude hydrogen gas. It is led to a catalytic reactor 4 where it is converted into water. As a catalyst for this purpose, a palladium-based catalyst is suitable, and a commercially available palladium-based catalyst for oxygen-water conversion can be used.

The hydrogen gas treated in this way is then transferred to valve 5
The water in the hydrogen gas generated in the reactor is adsorbed and removed by the adsorbent. Examples of this adsorbent include molecular sieve 5A, molecular sieving carbon, silica
Gel, activated alumina, activated carbon, etc. can be used.

Note that carbon dioxide, sulfur dioxide, etc. are also adsorbed and removed by this adsorbent.

On the other hand, it is already known that -carbon oxide can be converted into carbon dioxide by a platinum-based catalyst or other catalyst in the presence of oxygen. A catalytic reactor (not shown) for carbon monoxide to carbon dioxide conversion can be provided in front of the vessel.

The hydrogen gas treated in the adsorbent vessel is then filled under pressure into the metal hydride vessel 1° via a pipe 9 equipped with a valve 8. Here, the impurity gases that the hydrogen gas still contains are mostly inert gases, nitrogen, methane, etc. that have extremely weak adsorption properties to metal hydrides due to the above series of treatments, so hydrogen gas selectively absorbs metal hydrides. While the impurity gas is occluded by the hydride, the impurity gas is not occluded by the metal hydride.
Remains in container. Therefore, after filling the metal hydride container with hydrogen at a predetermined pressure, close the valve 8 and the valve 12 on the purified hydrogen gas supply pipe ll, and open the purge valve 14 on the purge pipe 13 to drain the gas in the container. If a portion of the gas is released from the container, the impurity gas mentioned above will be removed from the container. Therefore, if the valve 12 is then opened and hydrogen gas is released from the metal hydride, preferably near the hydrogen equilibrium decomposition pressure of the metal hydride, this hydrogen gas can be obtained as purified hydrogen gas from the hydrogen supply pipe 11. can.

Although the metal hydride used in the present invention is not particularly limited, according to the apparatus of the present invention, oxygen and water are removed in advance before filling the crude hydrogen gas into the metal hydride container, as described above. Therefore, metal hydrides made of rare earth element alloys that are susceptible to oxidative deterioration can also be suitably used, and such metal hydrides are also inexpensive. Examples of metal hydrides made of rare earth elements include LaNi, LaNi 4.7A, etc.
Examples include 3.5 MmNi4,5 AlCl,5 (Mm means mitshu metal). In addition to these, iron-based alloys, magnesium-based alloys, etc. can also be used.

As described above, according to the apparatus of the present invention, crude hydrogen gas is treated in advance to substantially remove oxygen and water that poison metal hydrides, as well as impurity gas components that are strongly adsorbed on the surface of metal hydrides. Since the metal hydride is charged into a metal hydride container after being removed and stored in the metal hydride, the metal hydride does not deteriorate, and the purity of the purified hydrogen gas obtained does not fluctuate. Furthermore, even if the hydrogen gas introduced into the metal hydride container still contains impurity gases, most of the impurity gases are gases that have extremely weak adsorption to metal hydrides. Therefore, these impurity gases can be easily removed from the metal hydride container by purging the container after filling the metal hydride container with hydrogen gas at a predetermined pressure. In this way, according to the apparatus of the present invention, purified hydrogen gas can be stably obtained over a long period of time without deterioration of the metal hydride.

The present invention will be explained below with reference to Examples.

Example In the apparatus shown in FIG. 1, a commercially available granular palladium catalyst was used in the catalytic reactor, Molecular Sieve 5A was used as the adsorbent in the adsorbent container, and LaNi was used as the metal hydride.
5 was used to treat industrial hydrogen gas with a hydrogen purity of 99.99%, an oxygen content of 5 ppm, and a water content of 40 ppm at room temperature, and finally hydrogen gas was introduced into a metal hydride container at a pressure of 8 kg/cnT. Filled. The water content in the hydrogen gas treated in the catalytic reactor and adsorbent vessel is approximately 0.5 ppm.
, oxygen is about 0. It was lppm.

After opening the purge valve and releasing 5% of the gas from the container, purified hydrogen gas was obtained from the hydrogen supply pipe.

This hydrogen gas is detected using a gas chromatograph (detector TcD,
It had a high purity of 99.9999% or more, which exceeded the detection limit of T i D).

FIG. 2 shows the relative change over time in the hydrogen storage capacity of the metal hydride when the crude hydrogen gas purification operation as described above is repeated, with the initial value being 100.

In addition, for comparison, the same industrial hydrogen gas as above was directly filled into a metal hydride container, and the relative hydrogen storage capacity of the metal hydride was changed over time when the operation of refining the hydrogen gas was repeated. These are also shown in Figure 2. According to the latter method for comparison, after 104 cycles the hydrogen storage capacity of the metal hydride decreases to 50% of its original value;
According to the device of the present invention, even after 10 cycles, 70%
It holds more than that. Furthermore, the hydrogen gas at this time also maintained a high purity exceeding the detection limit of the gas chromatograph, as described above.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing an embodiment of the hydrogen gas purification device of the present invention, and Fig. 2 shows the change over time in the hydrogen storage capacity of the metal hydride in the metal hydride container by the device of the present invention and the conventional device. This is a graph showing. l...Hydrogen storage container, 4...Catalytic reactor, 7...
Adsorbent container, 10... Metal hydride container, 11...
Purified hydrogen gas supply pipe, 14...purge valve. Patent applicant Mototoshi Fujinuma, representative of Sekisui Chemical Co., Ltd.

Claims (1)

[Claims] (11) A catalytic reactor for catalytically converting oxygen in crude hydrogen gas into water, an adsorbent container for adsorbing and removing water in the hydrogen from this reactor, and an adsorbent container for absorbing and releasing hydrogen gas from this adsorbent container. 1. A hydrogen gas purification apparatus, comprising: a metal hydride container filled with a metal hydride capable of producing purified hydrogen gas.